Biometrics and screening of kale (Brassica oleracea var. acephala) half-sib progenies obtained by recurrent selection in Brazil

Kale is one of the main leafy vegetables grown in Brazil. However, genetic breeding programs for the development of superior cultivars are scarce. Thus, the objective of this study was to select promising genotypes and to obtain strategic information for the genetic improvement of kale from plant biometrics. The study was conducted in two stages in the horticulture sector of Universidade Federal dos Vales do Jequitinhonha e Mucuri (UFVJM) during 2018 and 2019. The university is located in the municipality of Diamantina, state of Minas Gerais, Brazil. The seeds used were obtained from 25 pre-selected half-sib progenies. In 2018, these progenies were recombined, selecting the seeds from plants with superior agronomic performance. Subsequently, in the year 2019, the seeds harvested in the first stage were sown, and the agronomic evaluation of the resulting plants was conducted. The experimental design was randomized blocks with four replicates and six plants per plot. At this stage, agronomic biometrics of the plants were conducted, identifying those with higher productivity and leaf quality. The genetic parameters were estimated, and the genetic gains with selection were predicted. The highest individual heritability in the narrow sense (h²_a) was observed for plant height, followed by the mean mass per leaf. The yield of leaves showed gains of 11.80, 10.39, and 7.68% at selection intensities of 10, 15, and 30%, respectively, indicating the possibility of genetic progress with the selection of superior genotypes. The individual selection approach proved effective in improving the population, however, indirect selection for increased leaf number resulted in a reduction in leaf size.